You can varnish over paints and bare wood, but can you apply varnish over stain?
You can apply varnish over the stain. That’s because varnish is a clear top coat that will protect the wood stain and the material underneath. Also, since varnish is a clear coat (has no color), it won’t interfere with the wood stain color.
Varnish sticks well to a stained surface because varnish doesn’t need to penetrate the surface to stick. In addition, the varnish will protect the wood stain from moisture, water, and scratches.
This post reveals more about applying varnish after staining, including the steps to carry out the task. So let’s dig in.
Stain Must Dry Before Applying Varnish
The stain must cure before you apply varnish over it. For instance, the wood stain cures within 3 days. However, the cure (and dry) time of the stain depends on the brand and type of the stain.
For example, a water-based stain cures within 2 days, while an oil-based stain takes 3 days to cure. That’s because these two types of stain use different paint solvents. For the stain to dry and cure, the solvent must evaporate, and the stain coating must oxidize (harden). Since water evaporates faster than oil, the water-based stain dries faster.
Applying varnish before the stain is dry will make the finish sticky and peel off. That’s because once you apply varnish, the evaporation process of the paint solvent is stopped. Since the stain solvent can’t evaporate and the paint particles can’t harden, the finish will turn tacky and won’t dry.
So, it’s best to wait until the stain is fully dry (cured) before you apply varnish over it.
Related Read: Varnish vs Stain?
How To Apply Varnish Over Stain?
Applying varnish over wood stains is necessary for outdoor surfaces. That’s because the varnish will protect the stain from harsh weather elements such as rain.
Applying varnish over stain is easy, but you need a few tools:
- Dish Soap
- Sponge or Wire brush
- A bowl of water
- Medium-grit sandpaper
- Fine-grit sandpaper
- Spray gun or paintbrush
- Water-based Primer
- Varnish (Satin, medium, or high-gloss)
1. Prepare the work area
First, prep the work area. Bad finishes are often a result of improper preparation.
You must remove nearby objects and cover those objects you can’t move. Use painter’s tape over the parts of the surface you don’t want to apply varnish on.
2. Wash and Clean The Stain
Before you apply varnish over the stain, you must clean the stained surface. That’s because dust and grease will settle over the surface while the stain is drying. The varnish won’t stick or protect the surface well if you don’t remove the dust from the surface.
To wash an old stained surface:
- Mix dish soap with water.
- Pour the soapy water over the surface.
- Use a soft brush to clean the surface.
- Rinse with clean water.
If the stain was recently applied, you don’t need to wash it; just use a clean rag to wipe off the surface.
Also, if the stain was previously sealed with a top coat, you must remove the sealant first.
3. Scuff The Stain
To help the varnish stick better, you must sand or scruff the stained surface. Sanding will remove the imperfections from the stained surface and create small ridges to allow varnish to stick.
To sand a stained surface, start with 150-grit sandpaper and end with fine-grit sandpaper (220-grit). This helps to achieve a smooth and fine finish.
However, if the stain is flaky, swollen, or loose, it’s best to remove the entire coating rather than sand it. If you apply varnish over a loose or flaky stain surface, the finish will look worn out. To remove old stains from a surface, use a paint stripping compound.
4. Apply The Varnish
You don’t need to apply a primer before using varnish over the stain. That’s because the primer will cover the color of the wood stain, and the finish will look dull. However, you can apply a primer coating if you don’t want the wood stain color to show after the finish is dry.
Once the stained surface is dry, clean, and sanded, you can apply the varnish. To apply varnish over the stain, use a sprayer. That’s because a sprayer will help you cover large areas faster and archive an even finish.
You can use a paintbrush or paint roller to apply varnish too. But since varnish requires detail, you need more than 1 paintbrush. Since angled or chiseled paintbrushes can get in corners, they are ideal for applying varnish on furniture.
Also, you must match the stain and varnish. For oil-based wood stains, use oil-based varnish. For water-based stains, use water-based varnish. You can also choose a dry or satin varnish, medium gloss, or high-gloss varnish.
You must apply 2-3 coats of varnish over a stained surface. Wait for each coat to dry before applying the next one.
Mixing Stain With Varnish
You can mix stain and varnish to get a colorful and durable finish. Since varnish is a clear coat, it doesn’t have paint pigments or colorant in the paint coating. Therefore, when dry, the varnish is clear and not tinted.
On the other hand, the wood stain has a lot of paint pigments (or colorants) in the paint coating but doesn’t have additives that make it resistant to water or durable. So, if you mix varnish and stain, you will get a colorful finish resistant to water, moisture, and scratches.
However, you must match the type of the varnish and stain. This means only mixing oil-based varnish and stain and water-based varnish and stain together.
If you mix water-based stain with oil-based varnish, the mixture will be inconsistent and won’t stick. The same applies if you mix oil-based stain with water-based varnish.
Applying Stain Over Varnish
You can’t apply stain over varnish unless you remove or sand the varnish first. That’s because varnish produces a protective sealant that repels moisture, including the wood stain. And, since wood stain can’t penetrate the surface, it won’t stick.
However, if you sand or remove the varnish, the wood stain will stick. That’s because sanding will create tiny ridges (holes) for the wood stain to soak (penetrate) into. But, the finish won’t be as durable. So, to get the best result, you must remove the glossy finish of varnish first and then apply a wood stain.
So, applying stain over varnish isn’t a good idea. That’s because wood stains are designed to alter the color of wood grain and won’t adhere to varnish properly. Also, putting stain over varnish is a waste of both paints. Stain is not durable or strong, so it will wear off or fade if used on varnish.
Related Read: Does Wood Stain Protect Wood?
You can apply varnish after stain, but the stain must be fully dry, and you must match the type (oil or water-based). Varnish will protect the wood stain and the surface underneath from water, moisture, scratches, and other damage.
However, you can’t apply stain over varnish. That’s because stain can’t penetrate the varnish layer and won’t stick.